Driving arrangement for liquid crystal display in timepieces

ABSTRACT

A driving arrangement for liquid crystal displays for timepieces wherein the relatively low voltage of a battery is stepped up in response to the oscillating frequency of the time standard oscillator for application to the liquid crystal displays. Where said time standard vibrator is a piezo-electrically driven tuning fork type vibrator, the driving signal for said vibrator is also obtained from the secondary of the step-up transformer.

BEG-332 Saito DRIVING ARRANGEMENT FOR LIQUID CRYSTAL DISPLAY INTIMEPIECES FOREIGN PATENTS OR APPLICATIONS l.()23,668 3/1966 GreatBritain 58/23 A [75] Inventor: Toshiaki Saito, Suwa, Japan [73]Assignee: Kabushiki Kaisha Suwa Seikosha, Primary Examiner-Richard B.Wilkinson Tokyo, Japan Assistant Examiner-Edith C. Simmons Jackmon [22]Filed, Jan 28 1972 AttrneyAlex Friedman et al.

[21] Appl. No.: 221,687

on V H V I M H V RAC Foreign Application Priority Data I F b 3 1971 Jaan 46/3769 A driving arrangement for liquid crystal displays for e ptimepieces wherein the relatively low voltage of a battery is stepped upin response to the oscillating fre- [52] Cl 58/50 58/23 fi g fz quencyof the time standard oscillator for application to the liquid crystaldisplays. Where said time standard 2 gi %7 g5 3 42? vibrator is apiezo-electrically driven tuning fork type 1 0 7 "g "i 5 168 vibrator,the driving signal for said vibrator is also ob- 6 4' 350/l tained fromthe secondary of the step-up transformer.

[56] References Cited 4 Claims, 1 Drawing Figure UNlTED STATES PATENTS3,664,1l6 5/1972 Emerson et al. 58/50 R X I! I" f 1 u v DRIVINGARRANGEMENT FOR LIQUID CRYSTAL DISPLAY IN TIMEPIECES BACKGROUND OF THEINVENTION This invention relates to timepieces provided with liquidcrystal displays. The voltage for actuating such liquid crystal displaysin timepieces is about 20-40 volts, a value much greater than thevoltage of the battery customarily incorporated in such timepieces,especially where such timepieces are watches. The battery incorporatedin watches is usually of the button-type having a voltage of about1.3-1.5 volts, the limited space in a watch preventing the use ofseveral batteries. By providing means for boosting the voltage of thebattery, liquid crystal displays may be incorporated in such timepieces.

SUMMARY OF THE INVENTION Generally speaking, in accordance with theinvention, a timepiece is provided including liquid crystal displaymeans, a battery, time standard vibrator means, and step-up transformermeans. First circuit means are provided for alternately connecting saidbattery to the primary of said step-up transformer means in response tothe oscillation frequency of said time standard vibrator means whilesecond circuit means is provided connecting said liquid crystal displaymeans to the secondary of said step-up transformer means and forselectively actuating said liquid crystal display means to provide timeindication.

Said time standard vibrators may include a piezoelectrically driventuning fork type vibrator means having a piezo-electric driving elementand a piez-electric detecting element, said first circuit meansdetecting said time standard vibrator means frequency at saidpiezo-electric detecting element. Said piezo-electric driving elementmay be connected to said secondary of said step-up transformer means.

Accordingly, it is an object of this invention to provide a time-piecewherein a relatively low voltage battery may drive a liquid crystaldisplay device.

A further object of the invention is to provide a timepiece wherein theliquid crystal display device is driven by a relatively low voltagebattery and a piezoelectrically driven tuning fork type vibrator.

Still other objects and advantages of the invention will in part beobvious arid will in part be apparent from the specification anddrawing.

The invention accordingly comprises the features of construction,combinations of elements, and arrangement of parts which will beexemplified in the'constructions hereinafter set forth, and the scope ofthe invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWING For a fuller understanding of theinvention, reference is had to the following description taken inconnection with the accompanying drawing, in which:

The FIGURE is a circuit diagram depicting one embodiment of thearrangement according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The driving arrangement forliquid crystal displays for timepieces according to the invention isdepicted in the FIGURE, wherein a tuning fork type vibrator l isprovided as a time standard. Said vibrator is provided with a detectingpiezo-electric element 2 for detecting the vibration thereof and adriving piezo-electric element 3 for exciting the vibration thereof. Atransistor 7 is provided connected at its base to detectingpiezoelectric element 2. Diode 5 is connected between the emitter andbase of transistor 6 for bias adjustment while a base leak resistor 4 isprovided connected to the base of said transistor.

A direct current source 7 is connected in series with the primary coil 8of a step-up transformer and the emitter-collector path of transistor 6.The secondary coil 9 of said transformer is connected between thecollector of said transistor and a liquid crystal display element 10.Driving piezo-electric element 3 is connected to the terminal ofsecondary coil 9 to which said liquid crystal display element isconnected.

A switching transistor 11 is connected with its emitter-collector pathin series with liquid crystal display element 10.

When the tuning fork type vibrator 1 oscillates, a voltage is producedin detecting piezo-electric element 2 and an alternating current isapplied to the base of transistor 6. This current is amplified bytransistor 6 to produce a voltage at both ends of primary coil 8, whichvoltage is stepped up by the transformer to produce a higher voltage atsecondary coil 9. This higher voltage is applied to drivingpiezo-electric element 3 for driving the tuning-fork type vibrator l andfor sustaining such vibrations.

The high frequency output of the tuning fork vibrator l is divided intotime signals in the usual manner, such time signals being representativeof seconds, minutes and hours, as desired. Liquid crystal element 10depicted in the drawing is representative of a matrix of such elementsproviding a digitial time indication when suitable combinations thereofare actuated. At the instant that the liquid crystal display element 10depicted in the drawing is to be actuated, a time signal 12 produced bya matrix circuit (not shown) from the output signal of the time standardvibrator, is applied to the base of transistor 11 to render saidtransistor conductive so that the stepped up voltage is supplied to theliquid crystal display element. Each of the liquid crystal displayelements of the display matrix would be provided with a separateswitching transistor, the required combination of such display elementsfor the display of present time being simultaneously actuated inresponse to such time signals.

The arrangement according to the invention permits the driving of liquidcrystal display elements by means of a DC. electric source of lowvoltage such as a mercury battery of 1.3 volts or a silver battery of1.5 volts.

Further, the arrangement according to the invention permits theprovision of a compact structure suitable for watches wherein space islimited. In such constructions, it is most convenient to use a tuningfork type vibrator which is of small size and produces a relatively lowfrequency, so as to permit the direct use of the frequency of thevibrator for stepping up the voltage of the electric source. However,the arrangement according to the invention is not limited to a metallictuning fork, but may also be applied to a quartz crystal vibrator.

The connection between driving piezo-electric element 3 and thesecondary coil 9 of the transformer provides a driving voltage of avalue suitable for driving the piezo-electrically driven tuning forktype vibrator. Such vibrators require a voltage of about 20 volts forproper driving. The arrangement according to the invention provides thisvoltage while permitting reduction in the area occupied by thetransformer which is fairly large, thereby resulting in a cost savings.

It will thus be seen that the objects set forth above, and those madeapparent from the preceding description, are efficiently attained and,since certain changes may be made in the above constructions withoutdeparting from the spirit and scope of the invention, it is intendedthat all matter contained in the above description or shown in theaccompanying drawing shall be interpreted as illustrative and not in alimiting sense.

It is also to be understood that the following claims are intended tocover all of the generic and specific features of the invention hereindescribed, and all statements of the scope of the invention which, as amatter of language, might be said to fall therebetween.

What is claimed is:

l. A timepiece comprising liquid crystal display means; time standardvibrator means; DC. voltage source means; step-up transformer meanshaving a primary and a secondary; first circuit means operativelycoupling said DC. voltage source means and said stepup transformer meansprimary and being coupled to said vibrator means for alternatelyconnecting said DC. voltage source means to said step-up transformermeans in response to the frequency of oscillation of said time standardvibrator; and second circuit means operatively connecting said liquidcrystal display means to said step-up transformer means secondary andfor the selective actuation of said liquid crystal display means fortime indication.

2. A timepiece as recited in claim 1, wherein said time standardvibrator is a piezo-electrically driven tuning fork type vibrator meanshaving a detecting piezoelectric element and a driving piezo-electricelement, said first circuit means being connected to said vibrator meansat said detecting piezo-electric element.

3. A timepiece as recited in claim 2, wherein said drivingpiezo-electric element and said liquid crystal display means areconnected together to said step-up transformer means secondary.

4. A timepiece as recited in claim 2, wherein said first circuit meansincludes a transistor means connected with its emitter-collector path inseries with said DC. voltage source means and said step-up transformermeans primary, the base of said transistor being connected to saiddetecting piezo-electric element.

1. A timepiece comprising liquid crystal display means; time standardvibrator means; D.C. voltage source means; step-up transformer meanshaving a primary and a secondary; first circuit means operativelycoupling said D.C. voltage source means and said step-up transformermeans primary and being coupled to said vibrator means for alternatelyconnecting said D.C. voltage source means to said step-up transformermeans in response to the frequency of oscillation of said time standardvibrator; and second circuit means operatively connecting said liquidcrystal display means to said step-up transformer means secondary andfor the selective actuation of said liquid crystal display means fortime indication.
 2. A timepiece as recited in claim 1, wherein said timestandard vibrator is a piezo-electrically driven tuning fork typevibrator means having a detecting piezo-electric element and a drivingpiezo-electric element, said first circuit means being connected to saidvibrator means at said detecting piezo-electric element.
 3. A timepieceas recited in claim 2, wherein said driving piezo-electric element andsaid liquid crystal display means are connected together to said step-uptransformer means secondary.
 4. A timepiece as recited in claim 2,wherein said first circuit means includes a transistor means connectedwith its emitter-collector path in series with said D.C. voltage sourcemeans and said step-up transformer means primary, the base of saidtransistor being connected to said detecting piezo-electric element.